title: Effect of dantrolene on KCl- or NMDA-induced intracellular Ca2+ changes and spontaneous Ca2+ oscillation in cultured rat frontal cortical neurons.
abstract: Dantrolene has been known to affect intracellular Ca2+ concentration ([Ca2+]i) by inhibiting Ca2+ release from intracellular stores in cultured neurons. We were interested in examining this property of dantrolene in influencing the [Ca2+]i affected by the NMDA receptor ligands, KCl, L-type Ca2+ channel blocker nifedipine, and two other intracellular Ca2(+)-mobilizing agents caffeine and bradykinin. Effect of dantrolene on the spontaneous oscillation of [Ca2+]i was also examined. Dantrolene in microM concentrations dose-dependently inhibited the increase in [Ca2+]i elicited by NMDA and KCl. AP-5, MK-801 (NMDA antagonists), and nifedipine respectively reduced the NMDA and KCl-induced increase in [Ca2+]i. Dantrolene, added to the buffer solution together with the antagonists or nifedipine, caused a further reduction in [Ca2+]i to a degree similar to that seen with dantrolene alone inhibiting the increase in [Ca2+]i caused by NMDA or KCl. At 30 microM, dantrolene partially inhibited caffeine-induced increase in [Ca2+]i whereas it has no effect on the bradykinin-induced change in [Ca2+]i. The spontaneous oscillation of [Ca2+]i in frontal cortical neurons was reduced both in amplitude and in base line concentration in the presence of 10 microM dantrolene. Our results indicate that dantrolene's mobilizing effects on intracellular Ca2+ stores operate independently from the influxed Ca2+ and that a component of the apparent increase in [Ca2+]i elicited by NMDA or KCl represents a dantrolene-sensitive Ca2+ release from intracellular stores. Results also suggest that dantrolene does not affect the IP3-gated release of intracellular Ca2+ and that the spontaneous Ca2+ oscillation is, at least partially, under the control of Ca2+ mobilization from internal stores.
authors.affiliation: Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hayashi
authors.forename: A
authors.initials: A
authors.lastname: Kagaya
authors.forename: M
authors.initials: M
authors.lastname: Takebayashi
authors.forename: T
authors.initials: T
authors.lastname: Oyamada
authors.forename: M
authors.initials: M
authors.lastname: Inagaki
authors.forename: Y
authors.initials: Y
authors.lastname: Tawara
authors.forename: N
authors.initials: N
authors.lastname: Yokota
authors.forename: J
authors.initials: J
authors.lastname: Horiguchi
authors.forename: T P
authors.initials: TP
authors.lastname: Su
authors.forename: S
authors.initials: S
authors.lastname: Yamawaki
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D003620:Dantrolene / Q000494:pharmacology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005625:Frontal Lobe / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects
chemical_list: D002121:Calcium Channel Blockers; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D011189:Potassium Chloride; D003620:Dantrolene; D002118:Calcium